Your reason for believing this lies entirely within the Bible. I hardly consider a 1500 year old book "making clear what he wants". Particularly given that even among those who believe the book, they still can't agree on what God wants. And of course, that doesn't even beging to address the issue of all the other holy books which contradict the Christian Bible. You may personally believe that you know what God wants, but if so it's not because God has been clear about it.
Label: Sarcastic